How McLaren has 'shoehorned' Mercedes engine into its MCL35M

McLaren's decision to change power unit supplier over the winter has naturally led to a myriad of problems that have had to be solved ahead of the new Formula 1 season.

McLaren is no stranger to such issues as this is the third time in the past seven years it has opted to fit a new system into one of its cars after changing from Mercedes to Honda for 2015, Honda to Renault three years later, and now back to Mercedes from Renault.

The Woking-based team clearly likes to do things the hard way, but it is a path it has deemed necessary to take in order to power its way back to the front as it is now over eight years since McLaren last won a grand prix.

For this season, McLaren has had to effectively design a new car in order to integrate the Mercedes power unit, while there have also been changes in a number of areas, including gearbox, cooling, electricals and the energy store.

The new PU and changes to the chassis meant McLaren was forced to use up its two development tokens for this season, leading to greater refinement aerodynamically at the rear, although not quite to 'size zero' - a phrase coined by former team boss Ron Dennis - of the Honda system when it was introduced into the MP4-30.

But there have naturally been numerous hurdles along the way. Explaining what has been overcome, technical director James Key said: “We have done this through a period where the cars were homologated last year, mechanically.

"So a lot of the components in the engine slot were frozen at the beginning of last season, and this actually put us in a bit of a spot.

"But there were allowances for that and then we had to undertake what was a very different installation. Every engine installation is really quite different. There is no one solution – the sizing of the various components can affect the car's architecture.

“So what we needed to try and do is respect the homologation process by not changing things we didn’t really need to change, but clearly make the changes we need to the homologated parts.

"That was to change the chassis which, of course, has to change with a new engine, the energy store, aspects of the gearbox for packaging purposes, the electrical system, and the cooling systems are completely different as well.

“Fundamentally, the architecture of the car is quite different but the homologated areas we need to stick to are as unaffected as possible.

"In amongst all of the challenges of trying to get this done, it added an extra dimension which led to a somewhat sub-optimal approach compared to if you were completely free but I don’t think it was that much of a compromise.”

Key claims that with regard to the actual installation "there are pros and cons" and it remains to be seen just how much McLaren has had to compromise in order to find the competitiveness it craves in comparison to its works rival.

Expanding on the details, Key added: "You have got the front-mounted compressor versus the hole for the compressor at the rear. That meant quite significant changes for how you lay out.

"Mercedes’ installation is certainly tidy. You can see how much attention to detail has gone into it. It is a straightforward package in that respect.

"It has given us some plus points, equally, there are further demands on other areas that we have had to adjust the other way.

"I think what has become clear over the last few months is the Mercedes installation has become very good to work to in that respect.

"We had to install this engine in this homologated environment and I think working with our Mercedes colleagues has made it reasonably easier to shoehorn in this engine."

Key recognises that while McLaren is now partnered with the best PU supplier in F1, the offset is since the introduction of the current V6-hybrid systems in 2014, natural convergence means its rivals have significantly closed the gap.

With all the problems that have had to be overcome, the first qualifying session for the season-opening Bahrain Grand Prix will determine whether it has all been worth it.

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